1. Technical Field
This invention relates to medical appliances and, more particularly, to pelvic traction devices.
2. Discussion
Pelvic traction devices generally take the form of belts which encircle a supine patient's pelvic area. a weight is attached to the belt to provide a static tractive force to the sacral lumbar spine. As will appear, the patent literature discloses a wide variety of different pelvic traction belt constructions.
Some of the prior art designs have been developed to fit a wide size range of patients. an obvious advantage of these so-called "universal" belts is that it reduces inventory requirements for hospitals and other institutions that use these devices. U.S. Pat. Nos. 3,572,327 to Beard; U.S. Pat. No. 3,797,483 to Feldman and U.S. Pat. No. 3,872,860 to Noblitt disclose these types of traction devices. One of the disadvantages of such belts is that their lengths are so long that it often becomes necessary to overlap portions of the belt when it comes to fitting small patients. The overlapping portion of the belt often reaches under the spine of the patient causing discomfort. Also, the end of the belt used for fastening purposes can become located underneath the patient thereby increasing the difficulty in applyiing and removing the belt. The overlapping problem also limits the practical maximum size range attainable by these single pelvic belts since making the belt longer will just increase the overlapping problem.
Tractive forces are applied to pelvic belts to rotate and flatten the sacral lumbar spine as disclosed in, for example, in U.S. Pat. No. 3,960,146 to Albrecht, by lifting and pulling the pelvis. The pelvis can be pulled at various angles as disclosed in U.S. Pat. No. 4,073,290 to Farrar Jr. The forces are generally applied by hanging weights attached to the belt. However, the force from the weights cannot deliver the desired static tractive force to the spine until the static resistance between the belt and the bed is overcome. In other words, the pelvic area needs to slide in the direction of the applied tractive force while the upper torso remains stationary in order to relieve the stress on the spine. The aforementioned U.S. Pat. No. 3,960,146 discloses a flattened tube of satin for the purpose of reducing sliding friction. However, it appears that the tube will not stay in position during use and can bunch up under the patient's back causing him discomfort. In addition, the tube is intended to slide in a back and forth direction only. The design does not appear to acccommodate patient movement from side to side in the bed which is sometimes necessary.
U.S. Pat. Nos. 3,452,747 to Varco and 3,522,802 to Morton mention that some of the known pelvic belts tend to concentrate the forces onto the soft tissues over the iliac crests which cause painful pressure points. It would be desirable to redistribute these forces more evenly over as much of the pelvic area as possible in order to reduce painful pressure on the iliac crests.
The aforementioned patents to Beard, Feldman and Noblitt require that the straps connected to the traction weight must be adjusted for each patient. While such adjustment can be accomplished, it is somewhat bothersome and not always easy to quickly perform. Consequently, it would be desirable to have a permanently affixed means for applying a tractive force to the patient.